Mine's about 11 lbs off, and they had me try 10 different ways of grounding it with no change. Waiting for an engineer to call me back but was wondering if I'm wasting my time with it and should go another route. Was thinking of getting the manual in-cab one from autometer, but don't find it on their web-site, and I heard it had too many problems, so now I guess its the $190 Autometer electric...